Future of Drought
By Ryan Magnuson Drought Drought is defined as, “dryness of the weather or climate; lack of rain.”Oxford English Dictionary In most cases, droughts lead to devastating impacts on agriculture and ecosystems that can be felt years in the future. With damage to agricultural activities, drought can severely limit the food supplies of counties they affect. There is no question that these effects are felt strongest in developing nations where proper precautions against droughts, such as food reserves and drought sustainable farming techniques, have not been taken and consequently can lead to long term food shortages and, in some cases, severe famine.World Health Organization. "Climate Change and Health." World Health Organization. Last modified August 2014. Accessed February 25, 2015. http://www.who.int/mediacentre/factsheets/fs266/en/. Unfortunately, with the Earth’s global temperature increasing due to climate change, droughts are on the rise, and the WHO predicts that climate change will effectively “double the frequency of extreme droughts and increase their average duration six-fold.”Ibid Causes of Drought Drought is usually caused by a combination of three main contributors: land and sea surface temperatures, atmospheric circulation patterns, and soil moisture. Surface temperatures and soil moisture will usually regulate each other daily. As the ground heats up during the day, if there is moisture present, the soil water will evaporate and rise with the warmed air until it interacts with colder air found higher in the atmosphere. Once the vapor-rich warm air hits the cold air, it will condense and fall to the ground as precipitation. However, atmospheric circulation patterns, such as La Niña events, can cause dry air to sweep into an area and replace the vapor-rich air, thus removing the precipitate from the daily cycle. As the remaining moisture in the soil is evaporated, there will not be enough to condense and fall to the ground as precipitate, furthering removing more water from the environment and causing a drought.NASA. "Physical Processes That Cause Drought." Earth Observatory. Accessed February 23, 2015. http://earthobservatory.nasa.gov/Features/NAmerDrought/ NAmer_drought_2.php. Climate Change Over the past 100 years, the earth has been warming. In this time, the Earth’s average temperature has increased almost an entire degree Celsius, while warmer regions, the average temperature has increase upwards of five degrees.Wehner, Michael F. "Projections of Future Drought in the Continental United States and Mexico." World Climate Research Programme. Accessed February 25, 2015. http://drought.wcrp-climate.org/workshop/Talks/Wehner.pdf. While this doesn’t sound like a lot, the ramifications from this slight increase in temperature range from melting icecaps to decreased agricultural outputs. Additionally, climate change produces an increase in extreme weather events, including extreme precipitation events and lack thereof. Most of the increase in temperature and be observed as a direct result of human burning natural fuel reserves hidden under the Earth’s crust. Green House Gasses A green house gas is defined as a gas that acts as an insulator for earths atmosphere; light and heat will come in from the sun, but then the heat will not be able to escape the atmosphere because it is insulated by these greenhouse gasses. Carbon dioxide is one of the main gasses contributing to the modern day “greenhouse effect” we are experiencing. Ancient soil evidence has shown that the Earth goes through natural periods with increased or decreased carbon dioxide levels due to natural process such as fires or volcanoes.University of California, San Diego. "Carbon Dioxide through Geologic Time." Earth Guide. Accessed February 25, 2015. http://earthguide.ucsd.edu/ virtualmuseum/climatechange2/07_1.shtml. However, in recent years, human's combustion of carbon based fuels, i.e. wood, coal, oil, carbon dioxide levels in the Earth’s atmosphere have increased at a rate unprecedented in human history. In the past 200 years, we have virtually doubled carbon dioxide concentrations, from 260 ppm in 1800 to just over 400 ppm in early 2015, and, if humans continue on their current path of fossil fuel consumption, estimates for 2100 are set to well over 1000 ppm, which could vastly increase Earth's temperature and exponentially increase the amount of habitat destruction and extreme weather conditions. Ice Caps With an increase in Earth’s global temperature, the size of Earth’s ice caps has decrease drastically. Since 1970, when satellite recording of ice caps began, the surface area of the ice caps continues to decrease. In 2008, the northern ice cap extended over only 55% of the area it originally covered.Gran, Rani. "NASA Finds Thickest Parts of Arctic Ice Cap Melting Faster." NASA. Last modified February 29, 2012. Accessed February 23, 2015. http://www.nasa.gov/topics/earth/features/thick-melt.html. With the decrease in ice coverage at the poles, this has led to rising sea levels and an increase in the total volume of water in the hydrologic cycle. This results in more extreme water patterns across the globe, from monsoons to dry seasons. Correlation Between Climate Change and Droughts Globally, precipitation levels have actually increased in the past 100 years. Over land area’s world wide, annual precipitation levels actually increased by about .2% per decade.Environmental Protection Agency. "Climate Change Indicators in the United States." Environmental Protection Agency. Last modified December 23, 2014. Accessed February 25, 2015. http://www.epa.gov/climate/climatechange/ science/indicators/weather-climate/index.html. But although global precipitation levels have increased on average, local precipitation levels in areas already deemed at risk, such as much of Africa and South-West North America, have fallen considerably. The increase in global precipitation rates is a direct result of the ice caps melting due to climate change, as well as the direct relationship between temperature and evaporation rates, as temperature increases, so does the rate at which water evaporates. However, warmer air has the ability to hold more water. This accounts for the fact that in colder areas, annual precipitation amounts are steadily increasing, while in already warm areas, precipitation rates are steadily falling.National Oceanic and Atmospheric Administration. "Future Drought." National Climatic Data Center. Accessed February 25, 2015. http://www.ncdc.noaa.gov/ monitoring-references/dyk/future-drought. Consequences of Increasing Drought Soil Erosion As a drought sets in, the dry air will evaporate the remaining water moisture out of the soil. With less moisturee in the soil, fewer crops, and in extreme cases not even weeds,will develop. Without stable activity on the soil's surface, wind will churn up dry topsoil and turn it into sand. With a lack of topsoil, plants will be unable to uptake roots in the ground, and when rain falls, instead of plant growth, the effected area will experience floods and, thus, further erosion of topsoil and less future plant growth.NASA. "Physical Processes That Cause Drought." Earth Observatory. Accessed February 23, 2015. http://earthobservatory.nasa.gov/Features/NAmerDrought/ NAmer_drought_2.php. Topsoil can take up to 30 years to regenerate even one inch of damage, if given no further erosion, but this is unlikely because initial drought causes a positive-feedback loop where erosion causes more erosion.Government Of Canada. "Drought Increases Erosion Concerns." Agriculture and Agri-Food Canada. Last modified April 25, 2012. Accessed February 26, 2015. http://www.agr.gc.ca/eng/?id=1326746188555. This vicious cycle is what causes drought-affected regions, which are not promptly responded to, to undergo serious and essentially irriversabe soil damage; damage that can be felt generations later. Famine Due to soil erosion and lack of water availability, crop production in drought-affected regions drastically decreases. In the 1974 Ethiopian drought, soil erosion and lack of water become so bad, that even grazing grounds for cattle could not survive. This resulted in the starvation of 71% of all cattle in the country. Families who's livelyhoods depended on the sales of surplus food could not even produce enough food to meet their own needs, resulting in the widespread starvation of the population of the country.United Nations. "Effects of Drought on Farm Production and Livestock Holdings." Food and Agriculture Organization of the United Nations. Accessed February 26, 2015. http://www.fao.org/wairdocs/ILRI/x5446E/x5446e02.htm#TopOfPage. Similarly, in the recent Somalian drought, crop harvests were as low as 50% of normal, resulting food shortages and in 2 deaths per 10,000 people per day attributed to starvation.NASA. "Severe Drought Causes Famine in East Africa." Earth Observatory. Last modified july 23, 2011. Accessed February 26, 2015. http://earthobservatory.nasa.gov/IOTD/view.php?id=51411. The effects of these droughts kill hundreds of thousands, and poor countries like these will most likely take decades if not centuries to recover their food production industries. Conclusion When dry air weather patterns enter an environment already warmed through climate change, disaster strikes. Droughts ensue and land is rendered unusable for generations if proper actoins are not met. If the current trends of global temperature increase and decreased precipitation in warmer areas continue, mega-droughts and possibly even mass desertification will likely occur in what used to be some of Earth's most efficient farming regions. References